Coming from their manager, I suspect it could have also been meant as:

"Radical transparency doesn't mean you get to say negative things."

That isn't cognitive dissonance - it is doublespeak. Cognitive dissonance is when someone's mind unexpectedly encounters an internal contradiction and goes haywire trying to match assumptions up.

Old mate manager doesn't have any internal mental contradictions. They are explaining that the words have one meaning in the dictionary and another meaning when used together in the workplace. Well understood thing that happens everywhere.

As the author himself points out, nobody but him believed the corporate nonsense. This isn't cognitive dissonance, this is "You actually really believe these things?"